drivers: flash: stm32f4: resets OPTCR register #18296
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the current stm32f4 flash code assumes that it is run after reset. If a programm, like a bootloader, runs before the zephyr build firmware it can happen that the FLASH controller registers are changed. In my case this lead to failed read/write/erase operations. This fix addresses the stm32f4 flash driver. It clears the OPTCR register and take care, that the driver resets the flash settings to the reset defaults. Fixes #18263 Signed-off-by: Stefan Jaritz <stefan@kokoontech.com>
| @@ -329,6 +329,28 @@ static int stm32_flash_init(struct device *dev) | |||
| LL_AHB3_GRP1_EnableClock(LL_AHB3_GRP1_PERIPH_HSEM); | |||
| #endif /* CONFIG_SOC_SERIES_STM32WBX */ | |||
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| #ifdef CONFIG_SOC_SERIES_STM32F4X | |||
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Since we'll need dedicated code for each series, this will soon get unreadable.
For code genericity, please use a function that will be implemented in each series dedicated file.
| @@ -329,6 +329,28 @@ static int stm32_flash_init(struct device *dev) | |||
| LL_AHB3_GRP1_EnableClock(LL_AHB3_GRP1_PERIPH_HSEM); | |||
| #endif /* CONFIG_SOC_SERIES_STM32WBX */ | |||
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| #ifdef CONFIG_SOC_SERIES_STM32F4X | |||
| /* | |||
| * make sure that user options are disabled | |||
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"make sure that user options are disabled".
Well, this is your particular case. Other users may have correctly configured options they want to rely on.
And since this is the purpose of the option bytes, this should rather be the default behavior.
So I see this as a particular optional feature that should be default n.
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I leave it to the ST guys to maintain the stm32 drivers. I quickly adopted the coding style from the code above. Think maybe a reset function for the flash driver would be useful. This function can be implemented different for each stm32.
| return -EIO; | ||
| } | ||
| /* write reset config register content*/ | ||
| regs->optcr = 0x0FFFFFED; |
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Looking to 2 F4 variants ref man, I've found reset value to 0x0FFFAAED
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check RM0402 from st, it's the reference manual for the stm32f412 series. On page 77 you will find the value.
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This would work for F412 but not F401 not F446... at least, while this code will be used for all F4 series.
The reset of the flash controler is done once at the init of the flash driver. So it is not blindly. The current implementation of the flash driver running on a stm32f412 is not taking care of the OPTCR register settings. |
It is done irrespective of the other option bytes settings. |
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after discussing it with @erwango we decided to close this merge. Key points: I put the code to a git repro. so everyone can use this as a blueprint for similar problems. |
the current stm32f4 flash code assumes that it is run after reset.
If a programm, like a bootloader, runs before the zephyr build firmware
it can happen that the FLASH controller registers are changed. In my
case this lead to failed read/write/erase operations. This fix addresses
the stm32f4 flash driver. It clears the OPTCR register and take care,
that the driver resets the flash settings to the reset defaults.
Fixes #18263
Signed-off-by: Stefan Jaritz stefan@kokoontech.com